A resin-made gearing apparatus that includes a configuration in which only one tooth flank side of each tooth in one of a pair of gears is provided with an overhang section that is disposed on at least one end portion in a tooth width direction, and overhangs diagonally from the one tooth flank side toward the adjacent tooth side; an end portion in a tooth width direction of each tooth in the other gear is provided with a lightening section that is disposed in a tooth flank of each tooth on an end face on the side of the end portion corresponding to the overhang section of the one gear, so that when the opposite teeth of the pair of gears are meshed with each other, the overhang section of the one gear is elastically deformed and also the lightening section of the other gear is elastically deformed, to absorb a backlash. Thus, the backlash appearing at the meshing of the pair of rein-made gears is absorbed by a backlash absorbing section comprised of the overhang section and the lightening section, and also, the deformation of and stress in the backlash absorbing section are reduced.
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3. A resin-made gearing apparatus for transmitting a rotational motion between two shafts by an engagement of a pair of resin-made gears arranged to have opposite teeth meshed with each other, comprising a configuration wherein
only one tooth flank side of each tooth of one of the gears is provided with an overhang section that is disposed on at least one of end portions in a direction of tooth width, and overhangs diagonally from said one tooth flank side toward an adjacent tooth side to eliminate a backlash during a time when said pair of gears are meshed with each other;
only one tooth flank side of each tooth of the other gear is provided with an opposite overhang section that is disposed on an end portion, corresponding to said overhang section of said each tooth of the one gear, and overhangs diagonally from said one tooth flank side toward adjacent tooth side; and
said overhang section of the one gear as well as said opposite overhang section of the other gear are elastically deformed due to meshing of the teeth of said pair of gears during the rotation of said pair of gears, to thereby absorb a given amount of backlash.
1. A resin-made gearing apparatus for transmitting a rotational motion between two shafts by an engagement of a pair of resin-made gears arranged to have opposite teeth meshed with each other, comprising a configuration wherein
only one tooth flank side of each tooth in one of the gears is provided with an overhang section that is disposed on at least one of end portions in a direction of tooth width, and overhangs diagonally from said one tooth flank side toward an adjacent tooth side to eliminate a backlash during a time when said pair of gears are meshed with each other;
an end portion in a direction of a tooth width of each tooth of the other gear, corresponding to said overhang section of said each tooth of the one gear, is provided with a lightening section that is disposed at an end face on the side of the end portion and inside a profile of said each tooth of the other gear; and
said overhang section of the one gear as well as said lightening section of the other gear are elastically deformed due to meshing of the teeth of said pair of gears during the rotation of said pair of gears, to thereby absorb a given amount of backlash.
2. A resin-made gearing apparatus for transmitting a rotational motion between two shafts by an engagement of a pair of resin-made gears arranged to have opposite teeth meshed with each other, comprising a configuration wherein
both tooth flank sides of each tooth of one of the gears are provided with overhang sections that are disposed on at least one of end portions in a direction of tooth width, each of which overhangs diagonally from each of said both tooth flank sides toward an adjacent tooth side to eliminate a backlash during a time when said pair of gears are meshed with each other;
an end portion in a direction of a tooth width of each tooth of the other gear, corresponding to the overhang sections of said each tooth of the one gear, is provided with a lightening section that is disposed at an end face on the side of the end portion and inside a profile of said each tooth of the other gear; and
said overhang sections of the one gear as well as said lightening section of the other gear are elastically deformed due to meshing of the teeth of said pair of gears during the rotation of said pair of gears, to thereby absorb a given amount of backlash.
4. A resin-made gearing apparatus for transmitting a rotational motion between two shafts by an engagement of a pair of resin-made gears arranged to have opposite teeth meshed with each other, comprising a configuration wherein
both tooth flank sides of each tooth of one of the gears are provided with overhang sections that are disposed on at least one of end portions in a direction of tooth width, each of which overhangs diagonally from each of said both tooth flank sides toward an adjacent tooth side to eliminate a backlash during a time when said pair of gears are meshed with each other;
both tooth flank sides of each tooth of the other gear are provided with opposite overhang sections that are disposed on end portion, corresponding to said overhang sections of said each tooth of the one gear, each of which overhangs diagonally from each of said both tooth flank sides toward adjacent tooth sides; and
said overhang sections of the one gear as well as said opposite overhang sections of the other gear are elastically deformed due to meshing of the teeth of said pair of gears during the rotation of said pair of gears, to thereby absorb a given amount of backlash.
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1. Field of the Invention
The present invention relates to a gearing apparatus for transmitting a rotational motion between two shafts by assembling a pair of resin-made toothed wheels (it will be referred to as gears hereinafter) to engage opposite teeth with each other, and in particular, to a resin-made gearing apparatus for absorbing a given amount of backlash appearing upon engagement of the pair of gears by a backlash absorbing section and also for reducing the deformation and stress of the backlash absorbing section.
2. Description of the Related Art
The resin-made gearing apparatus of this type is characterized in that it is lightweight compared with a metal gearing apparatus, and also is capable to be used without the lubrication due to the self-lubricity thereof and in low noise. Further, the resin-made gearing apparatus, such as a molded plastic gear or the like, has a characteristic of high mass-production to achieve the reduction of product cost. Therefore, in recent years, the molded plastic gear has been widely used for a gear train in an ink jet printer, a gear train in a power transmission section of an automotive component or in a precision machine or instrument, and the like.
Here, generally, between teeth oppositely mating with each other in the assembly of a pair of gears, a clearance (play) called a backlash is disposed. This backlash is disposed for preventing the friction of a tooth surface of the gear due to a tooth profile error, an assembly error or the like, and also, for smoothing the meshing of the gear teeth.
However, in the recent gearing apparatus, the significantly high accuracy in the transmission of rotational motion is often required. For example, in certain types of angle sensors, it is required to transmit to the output side a detected angle at an absolute accuracy without involving any error. In this case, a backlash in the pair of meshed gears causes generation of an error in the transmission of rotational motion. Accordingly, there is a demand for a gearing apparatus whose backlash is constantly nil irrespective of an operative temperature environment or a dimensional error of the gears. As one measure for satisfying such a demand, a gear, which is free of backlash (it will be referred to as a backlash-less gear hereinafter) has conventionally been proposed.
According to the conventional backlash-less gear, as shown in
However, in the above described conventional backlash-less gear, the elastically deformable fin portion 52 is formed only on each end portion in the tooth width direction of each tooth, in one of the assembly of the pair of gears, but any contrivance is not provided on each tooth of the other meshed gear. Therefore, the fin portion 52 on the tooth in the one gear may be in direct contact with a tooth flank of the tooth of the other meshed gear so that both gears must be subjected to a high stress. Namely, although the fin portion 52 on each of the end portions in the tooth width direction in the one gear is elastically deformable, the tooth flank of each tooth in the other meshed gear forms a power transmitting plane which is not elastically deformed. Hence, the fin portion 52 in the one gear may come in contact with the power transmission plane, to be deformed to an extent exceeding an elastic limit range. In particular, in the case where the fin portion 52 in the one gear is consecutively formed along the periphery of the tooth profile to be folded in a U-shape at a tooth crest portion, the high stress mainly acts on the folded portion, and in an extreme case, it is deemed that the fin portion 52 of the tooth in the one gear is broken.
In view of the above problems, an object of the present invention is to provide a resin-made gearing apparatus for absorbing a given amount of backlash by a backlash absorbing section upon engagement of a pair of gears by meshing, and also for reducing a deformation and stress of the backlash absorbing section.
Taking the above-mentioned object into consideration, in accordance with a first aspect of the present invention, there is provided a resin-made gearing apparatus for transmitting a rotational motion between two shafts by an engagement of a pair of resin-made gears arranged to have opposite teeth meshed with each other, comprising a configuration wherein
only one tooth flank side of each tooth in one of the gears is provided with an overhang section that is disposed on at least one of end portions in a direction of tooth width, and overhangs diagonally from the one tooth flank side toward an adjacent tooth side to eliminate a backlash during a time when the pair of gears are meshed with each other;
an end portion in a direction of a tooth width of each tooth of the other gear, corresponding to the overhang section of the each tooth of the one gear, is provided with a lightening section that is disposed at an end face on the side of the end portion and inside a profile of the each tooth of the other gear; and
the overhang section of the one gear as well as the lightening section of the other gear are elastically deformed due to meshing of the teeth of the pair of gears during the rotation of the pair of gears, to thereby absorb a given amount of backlash.
According to such a configuration of the first aspect of the present invention, only the one tooth flank side of the one gear is provided with the overhang section that is disposed on at least one of the end portions in the tooth width direction, and overhangs diagonally from the one tooth flank side toward the adjacent tooth side, and the end portion in the tooth width direction of each tooth of the other gear is provided with the lightening section that is disposed at the end face on the side of the end portion, corresponding to the overhang section of the one gear, so that when the opposite teeth of the pair of gears are meshed with each other due to the rotation of the pair off gears, the overhang section of the one gear is elastically deformed and also the lightening section of the other gear is elastically deformed so as to absorb the given amount of backlash. Consequently, it is possible to absorb the backlash at the time of meshing of the pair of gears by the overhang section of the one gear and the lightening section of the other gear, and also, to reduce the deformation and stress in each of the overhang section and the lightening section.
Further, in accordance with a second aspect of the present invention, there is provided a resin-made gearing apparatus for transmitting a rotational motion between two shafts by an engagement of a pair of resin-made gears arranged to have opposite teeth meshed with each other, comprising a configuration wherein
both tooth flank sides of each tooth of one of the gears are provided with overhang sections that are disposed on at least one of end portions in a direction of tooth width, each of which overhangs diagonally from each of the both tooth flank sides toward an adjacent tooth side to eliminate a backlash during a time when the pair of gears are meshed with each other;
an end portion in a direction of a tooth width of each tooth of the other gear, corresponding to the overhang sections of the each tooth of the one gear, is provided with a lightening section that is disposed at an end face on the side of the end portion and inside a profile of the each tooth of the other gear; and
the overhang sections of the one gear as well as the lightening section of the other gear are elastically deformed due to meshing of the teeth of the pair of gears during the rotation of the pair of gears, to thereby absorb a given amount of backlash.
According to such a configuration of the second aspect of the present invention, both tooth flank sides of each tooth in the one gear are provided with the overhang sections that are disposed on at least one of the end portions in the tooth width direction, each of which overhangs diagonally from the one tooth flank side toward the adjacent tooth side, and the end portion in the tooth width direction of each tooth in the other gear is provide with the lightening section that is disposed at the end face on the side of each end portion corresponding to the overhang section of the one gear, so that when the opposite teeth of the pair of gears are meshed with each other, the overhang sections of the one gear are elastically deformed and also the lightening section of the other gear is elastically deformed so as to absorb the backlash. Consequently, it is possible to absorb the backlash at the meshing of the pair of gears by the overhang sections of the one gear and the lightening sections of the other gear, and also, to reduce the deformation and stress in each of the overhang section and the lightening section.
Moreover, in accordance with a third aspect of the present invention, there is provided a resin-made gearing apparatus for transmitting a rotational motion between two shafts by an engagement of a pair of resin-made gears arranged to have opposite teeth meshed with each other, comprising a configuration wherein
only one tooth flank side of each tooth of one of the gears is provided with an overhang section that is disposed on at least one of end portions in a direction of tooth width, and overhangs diagonally from the one tooth flank side toward an adjacent tooth side to eliminate a backlash during a time when the pair of gears are meshed with each other;
only one tooth flank side of each tooth of the other gear is provided with an opposite overhang section that is disposed on an end portion, corresponding to the overhang section of the each tooth of the one gear, and overhangs diagonally from the one tooth flank side toward adjacent tooth side; and
the overhang section of the one gear as well as the opposite overhang section of the other gear are elastically deformed due to meshing of the teeth of the pair of gears during the rotation of the pair of gears, to thereby absorb a given amount of backlash.
According to such a configuration of the third aspect of the present invention, only the one tooth flank side of each tooth in the one gear is provided with the overhang section that is disposed on at least one of the end portions in the tooth width direction, and overhangs diagonally from the one tooth flank side toward the adjacent tooth side, and only the one tooth flank side of each tooth in the other gear is provided with the opposite overhang section that is disposed on the end portion, corresponding to the overhang section of the one gear, and overhangs diagonally from the one tooth flank side toward the adjacent tooth side, so that when the opposite teeth of the pair of gears are meshed with each other during the rotation of the pair of gears, the overhang section of the one gear is elastically deformed and also the opposite overhang section of the other gear is elastically deformed so as to absorb the backlash. Consequently, it is possible to absorb the backlash during the meshing of the pair of resin-made gears by the overhang section of the one gear and the opposite overhang section of the other gear, and also, to reduce the deformation of and stress in each of the overhang section and the opposite overhang section. Further, in this case, since the overhang section of the one gear and the opposite overhang section of the other gear cooperatively absorb the backlash, an amount of overhanging of the overhang section of either one of both gears can be reduced to approximately a half, respectively.
Furthermore, in accordance with a fourth aspect of the present invention a resin-made gearing apparatus for transmitting a rotational motion between two shafts by an engagement of a pair of resin-made gears arranged to have opposite teeth meshed with each other, comprising a configuration wherein
both tooth flank sides of each tooth of one of the gears are provided with overhang sections that are disposed on at least one of end portions in a direction of tooth width, each of which overhangs diagonally from each of the both tooth flank sides toward an adjacent tooth side to eliminate a backlash during a time when the pair of gears are meshed with each other;
both tooth flank sides of each tooth of the other gear are provided with opposite overhang sections that are disposed on end portion, corresponding to the overhang sections of the each tooth of the one gear, each of which overhangs diagonally from each of the both tooth flank sides toward adjacent tooth sides; and
the overhang sections of the one gear as well as the opposite overhang sections of the other gear are elastically deformed due to meshing of the teeth of the pair of gears during the rotation of the pair of gears, to thereby absorb a given amount of backlash.
According to such a configuration of the fourth aspect of the present invention, both tooth flank sides of each tooth in one of the gears are provided with the overhang sections that are disposed on at least one of end portions in a tooth width direction, each of which overhangs diagonally from each of both tooth flank sides toward the adjacent tooth side, and both tooth flank sides of each tooth in the other gear are provided with the opposite overhang sections that are disposed on each end portion, corresponding to the overhang section of the one gear, each of which overhangs diagonally from each of both tooth flank sides toward the adjacent tooth side, so that when the opposite teeth of the pair of gears are meshed with each other, the overhang sections of the one gear are elastically deformed and also the opposite overhang sections of the other gear are elastically deformed so as to absorb the backlash. Consequently, it is possible to absorb the backlash at the meshing of the pair of gears by the overhang sections of the one gear and the opposite overhang sections of the other gear, and also, to reduce the deformation of and stress in each of the overhang section and the opposite overhang section. Further, in this case, since the backlash is absorbed by the overhang sections of the one gear and the opposite overhang sections of the other gear, an overhanging amount of each of the overhang section of the one gear can be reduced to approximately a half.
The other objects and features of the invention will become understood from the following description with reference to the accompanying drawings.
There will be described hereunder preferred embodiments of the present invention based on the appended drawings.
In the one gear G1, only on one tooth flank side of each tooth, an overhang section C is disposed on both of or one of end portions in a direction of tooth width (it will be referred to as a tooth width direction herein after), which overhangs diagonally from the one tooth flank side to the adjacent tooth side to eliminate a backlash during a time when the pair of gears G1 and G2 is in meshed engagement with each other due to the rotation of the pair of gears G1 and G2. Further, in the other gear G2, both of or one of end portions in a tooth width direction of each tooth are provided with a lightening section D that is provided as an unfilled portion disposed inside a tooth profile of each tooth on an end face on the side of the end portion corresponding to the overhang section C of the one gear G1.
Firstly, a shape of the one gear G1 will be described referring to
Then, as shown in
This overhang member 5 protrudes toward the adjacent tooth 2 by a dimension approximately same the backlash which is set between the tooth of the gear G1 and at least the tooth of the meshed gear G2, and a clearance 11 is formed between an end portion 10 of the tooth 2 and the overhang member 5. The clearance 11 has a depth thereof measured in the tooth width direction, which extends toward a position approximately coincident with a starting position P1 of the overhang member 5 and also extends from the tooth crest 7 to the bottom land 8 along the one tooth flank 6. As in the above manner, in the case where the clearance 11 is formed along the overhang member 5, when the overhang member 5 is pressed to be deformed by the tooth flank of the mating gear G2, the deformed overhang member 5 is received and accommodated in the clearance 11 so as to prevent the overhang member 5 from doing any counteraction against contacting of the gears G1 and G2 which are meshed with each other.
Namely, in the gear G1 in this embodiment, the other tooth flank 12 (on which the overhang member 5 is not formed) of the tooth 2 serves as a power transmission plane which is in contact with the tooth flank of the meshed gear G2 to transmit the rotational motion. In the case where the gear G1 is rotated in reverse to a main rotational direction to transmit the rotational motion, if the overhang member 5 is pressed to be deformed by the tooth flank of the meshed gear G2, the deformed overhang member 5 is accommodated in the clearance 11. Therefore, the overhang member 5 does not protrude from the one tooth flank 6 toward the outside, so that high rigid tooth flanks can be in contact with each other, to thereby enable the accurate transmission of the rotational motion even in the case where the gear G1 is rotated in reverse.
Here, as shown in
In the example shown in
Next, a description of a shape of the other gear G2 will be provided referring to
Then, as shown in
In the example shown in
Similarly to the embodiment shown in
In the example shown in
In this embodiment, since the backlash is absorbed by the overhang members 33 on the tooth flanks 6 and 12, an overhanging amount of each overhang member 33 can be made only approximately a half of an overhanging amount of the overhang member 27 as shown in
In the example shown in
Further, in the above description, as shown in
In such a case, the overhang members 5, 27 and 33 of the one gear G1, and the opposite overhang members of the other gear G2, absorb the backlash, and therefore, the overhang amount of each of the overhang members 5, 27 and 33 of the one gear G1 can be reduced to only approximately a half.
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